Science

Barcode Wales

Wales is the first nation in the world to have DNA barcoded all of its native flowering plants and conifers, opening up huge potential for research into biodiversity conservation and human health.

The Welsh flora DNA barcodes are freely available on the Barcode of Life Database (BOLD) for use by researchers around the world. The creation of this DNA barcode library is reported in the journal PLoS ONE.

Imagine you could identify any plant species in Wales from the tiniest fragment of leaf, seed or pollen grain; this is possible using DNA barcoding. This technique uses a small section of DNA to act as a unique identifier for that species. The first step is to assemble reference barcodes for the plants that we want to identify.

Here’s an example of the DNA barcode of spreading bellflower (Campanula patula), an herbarium specimen of the species and images of it in the wild

Once reference barcodes are in place, unknown DNA sequences can be compared to these in order to find out what they are. The real importance of the technique is that it can identify species from tiny fragments, different life stages, or from mixtures of samples. Species can be identified from pollen grains, fragments of seeds or roots, wood, faecal samples, stomach contents or environmental samples collected from the air, soil or water. Projects are now underway throughout the world to DNA barcode all living things and ensure that these barcodes are freely available online as a global resource. There are many potential applications of DNA barcoding for plants, for example we could:

Understand why pollinators are endangered. We are working with Swansea University on a project to understand the pollination role of hoverflies using DNA barcoding to identify the pollen grains carried on their bodies.

Understand the habitat requirements of endangered animals by finding out what plants they eat at different times of the year from faecal samples.

Potentially reconstruct past landscapes by identifying plants from seeds within the soil profile.

Help to understand how plant communities are assembled, vital for predicting the effect of climate change.

Could help to monitor the effects of hay fever by being able to identify exactly what pollen is in the atmosphere.

Could assist in forensic investigations by being able to identify plant fragments found on clothing or at crime scenes.

Improve animal health by analysing the exact composition of the diet of livestock in pastures.

Provide quality control for plant based products such as herbal medicines by identifying the constituent components.

Identify plants that are difficult to I.D. morphologically.

Vital to the establishment of DNA barcodes is having correctly identified source material, every reference barcode must have a voucher specimen so that its identity can be verified. We have used herbarium specimens from the National Museum Wales and the National Botanic Garden of Wales for most of our barcoding, as these are convenient to use and already verified. We also collected new specimens from plant species throughout Wales and the UK. A tiny fragment of the herbarium specimen is removed and the DNA extracted from this.

We then amplified the barcode DNA; for plants there are two barcode regions, sections of the genes rbcL and matK. These are recognised internationally so that everyone throughout the world uses a standard approach. Once the barcodes are amplified they are sequenced to find out the exact DNA code for that specimen for the two barcode regions. The completed barcodes are uploaded on to the Barcode of Life Databasealong with the voucher information and a scan of the herbarium specimen. For each species, we need to have multiple specimens barcoded, this allows us to spot errors and also to pick up if there is any variation within species in the barcode sequences. The Barcode Wales project has assembled over 5700 DNA barcodes. In total 98% of the Welsh native flora has DNA barcodes for rbcL and 90% for rbcL and matK.

So how effective are the DNA barcodes? Looking at the whole of Wales the DNA barcodes can distinguish up to 75% of native plant species. Looking at smaller scales, for any 10 km area of Wales, on average 82% of species can be distinguished and this rises to 93% for the species within any 2 km area.